Before a computing device may accomplish a desired task, it must receive an appropriate set of instructions. Executed by a device's processor(s), these instructions direct the operation of the device. These instructions can be stored in a memory of the computer. Instructions can invoke other instructions.
A computing device, such as a server, router, desktop computer, laptop, etc., and other devices having processor logic and memory, includes an operating system layer and an application layer to enable the device to perform various functions or roles. The operating system layer includes a “kernel” (i.e., master control program) that runs the computing device. The kernel provides task management, device management, and data management, among others. The kernel sets the standards for application programs that run on the computing device and controls resources used by application programs. The application layer includes programs, i.e., executable instructions, which are located above the operating system layer and accessible by a user. As used herein, “user space”, “user-mode”, or “application space” implies a layer of code which is less privileged and more directly accessible by users than the layer of code which is in the operating system layer or “kernel” space. The operating system layer has software programs that include a set of Application Program Interfaces (APIs). The language and/or message format of the APIs allow an operating system to interpret executable instructions received from program applications (e.g., service applications) in the application layer and return results to the program application.
When the execution of the program instructions call for data or other program instructions, the program will want to know where in memory the data or instructions are stored. In effect, the program will use a means for referencing or indexing where in memory the data or instructions are held. The kernel is responsible for virtual memory management. With virtual memory, a process is assigned its own virtual address space, which may not be available to other processes. In virtual memory a process has a logical view of memory that does not correspond to the actual layout of physical memory. When a process uses a virtual memory address the virtual memory system translates it into a physical address using a virtual to physical address mapping contained in some type of look up structure and address mapping database. Addresses exist for both software components and hardware. Physical addresses are partitioned into input/output (I/O) space and memory space. The I/O space is associated with peripheral hardware devices.
More and more operating systems (OSs) are interfacing with advanced configuration and power interface (ACPI) systems. ACPI provides power management, configuration, and other extended capabilities. ACPI is an open industry interface specification that provides a way of communicating system information from firmware to the OS and a means of providing runtime firmware control methods, as well as a set of fixed hardware for the OS to access. Operating systems include interpreters for handling instructions that are not fully compiled into machine code. Interpreters, such as may be used with ACPI, translate programs into machine language at runtime. Operating systems and the address space and interpreters they support may not be written to accommodate later developed system functionality. Likewise, an operating system may support a certain extended functionality only according to a specification version that was available when the operating system was released and not fully support later specification versions. One current area of system functionality expansion relates to “hotplug”. “Hotplug” is the ability to add and remove devices to a system without the need to shutdown or reset the system down. Another area of system functionality expansion relates to the ability to process 64 verses 32 bits of data.